In general, an electric motor is a device for converting an electric energy into a mechanical energy by using a force applied to a current charged conductor in a magnetic field, and is commonly referred to as a motor. The electric motor is classified into a DC motor and an AC motor in accordance with the type of power source. The AC motor is divided again into a three-phase AC motor and a single-phase AC motor, and the three-phase AC motor has been mainly used in recent years.
The electric motor is a device for converting the electric energy into a mechanical work by using a force applied to the current charged conductor in the magnetic field to mostly generate a power of a rotational movement.
Such an electric motor was begun to be made when electromagnetic induction was discovered by Faraday in around 1831. The early electric motor is a system which swings a movable unit to generate a power using attractive force/repulsive force of permanent magnets without rotating. In 1830, the DC motor having the same type as todays was initially made using an armature and electromagnets excited by DC, but it has a low power and is no more than a device in a level of research phase.
Thereafter, with finding a rotating magnetic field occurred in AC by Ferraris and Tesla as a momentum, two-phase AC motors were independently invented by them. After a three-phase AC motor having an output of 100 watts (W) was made in Germany for the first time by Dovrowelski in 1889, the three-phase AC motors are mainly used in recent years.
In addition, both of the DC motor and the AC motor operate by same principle, and when locating the current charged conductor in the magnetic field, an electromagnetic force (Lorentz force) occurs in a direction perpendicular to the direction of the magnetic field. When placing the magnets inside the electric motor to produce the magnetic field, and applying the current to a conductive wire connected to a rotor shaft, an electromagnetic force occurs. At this time, by the Fleming's left-hand rule, the rotor shaft rotates to generate the power. The electromagnetic force acting on the conductive wire is proportional to intensities of the magnetic field and current, and a length of the conductive wire.
Meanwhile, products commercially available from the market around us are industrial equipment developed with a focus on the function of a conventional power motor. However, recently, the power motor does not meet the needs of the times in terms of effective use of the energy, and as a result, there is a limit for applying the power motor to electric bicycles, electric motorcycles, electric cars, and the like. Accordingly, it is also an important problem to overcome such a limitation in application.
Further, in the equipment that requires a strong impelling force (torque), conventional cylinder motors employ a reduction gear for generating the power against the attractive force of the magnets and cores, or a system for satisfying a condition required to obtain a maximum function (load capacity) through a control compatible with voltage and current. However, the cylinder motors have complicated problems that it is difficult to effectively use a supplied electric energy due to a decrease in the inertia force and an overcurrent during starting, and a weight and manufacturing costs of a battery are increased.
For these problems, Korean Patent Registration Nos. 0988667 and 1025387, which have been filed and registered by the present applicant, disclose an electric motor in which coils are separately disposed in a radial shape into respective discs made of a nonmagnetic material, and rotating magnetic discs separately disposed in a radial shape are respectively installed on an upside and a downside of a fixing plate for separate coils at a predetermined interval, thus to provide the repulsive force and the electric-generating capacities, while inducing horizontal cross magnetic forces by a magnetic plate and a coil plate of the rotating disc.
However, the electric motor using the disc has a limitation in application that it should be installed in the equipment for providing the rotational movement, and the like, in terms of configuration. In particular, since the electric motor is formed in a disc shape, when increasing a size of the disc, there are problems that tightness is decreased due to an arrangement of the coils and magnets radially arranged on the circumference according to the structural nature thereof, and a loss of locomotive force occurs, and as a result, causing a decrease in electric-generating capacities and electric-generating speed.